Table 2.

Summary table for non-invasive biomarker candidates and related processes

Process of gut health	Biospecimen	Non-invasive biomarkers
Epithelial health and repair	Faeces	Reg1B
Intestinal barrier dysfunction and bacterial translocation	Blood and urine	Alpha-1-antitrypsin, lactulose/rhamnose ratio
Intestinal inflammation	Faeces	Myeloperoxidase, neopterin, calprotectin
Systemic inflammation	Blood	sCD14, CRP, AGP, KT ratio
Epigenetic metabolomes	Blood	LRP1
Enteric infection	Faeces, breath sample	TaqMan Array Card, SIBO
Nutrient malabsorption	Blood	Ferritin, zinc, GLP-2, pepsinogen I/II ratio
Celiac Disease screening	Blood	IgA tissue transglutaminase, total IgA

AGP, alpha 1-glycoprotein; CRP, C reactive protein; KT ratio, kynurenine/tryptophan ratio; LRP1, low density lipoprotein receptor-related protein 1; GLP-2, glucagon-like peptide-2; Reg1B, regenerating family member 1 beta proteins; sCD14, soluble cluster of differentiation 14; SIBO, small intestinal bacterial overgrowth.